Lasing without Inversion in Circuit Quantum Electrodynamics

TL;DR

This paper demonstrates the possibility of lasing without inversion in circuit quantum electrodynamics by leveraging environmental dissipation effects, which enhance photon emission over absorption, and discusses the conditions for experimental observation.

Contribution

It introduces the concept of lasing without inversion in circuit QED systems, highlighting the role of dissipation in enabling this phenomenon, which was previously considered elusive.

Findings

Lasing without inversion can occur in circuit QED systems due to environmental effects.

The effect is stronger than atomic recoil and should be observable with current technology.

System parameters and environment conditions are crucial for observing this phenomenon.

Abstract

We study the photon generation in a transmission line oscillator coupled to a driven qubit in the presence of a dissipative electromagnetic environment. It has been demonstrated previously that a population inversion in the qubit may lead to a lasing state of the oscillator. Here we show that the circuit can also exhibit the effect of "lasing without inversion". This is possible since the coupling to the dissipative environment enhances photon emission as compared to absorption, similar to the recoil effect which was predicted for atomic systems. While the recoil effect is very weak, and so far elusive, the effect described here should be observable with present circuits. We analyze the requirements for the system parameters and environment.